Anaplastic astrocytoma
| Anaplastic astrocytoma | |
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| Micrograph of an anaplastic astrocytoma. H&E stain. | |
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Anaplastic astrocytoma is a rare WHO grade III type of astrocytoma, which is a type of cancer of the brain. In the United States, the annual incidence rate for Anaplastic astrocytoma is 0.44 per 100,000 persons
Anaplastic astrocytomas fall under the category of high grade gliomas (WHO grade III-IV), which are pathologically undifferentiated gliomas that carry a poor clinical prognosis. Unlike glioblastomas (WHO grade IV), anaplastic astrocytomas lack vascular proliferation and necrosis on pathologic evaluation. Compared to grade II tumors, anaplastic astrocytomas are more cellular, demonstrate more atypia, and mitoses are seen.
Initial presenting symptoms most commonly are headache, depressed mental status, focal neurological deficits, and/or seizures. The growth rate and mean interval between onset of symptoms and diagnosis is approximately 1.5–2 years but is highly variable, being intermediate between that of low-grade astrocytomas and glioblastomas. Seizures are less common among patients with anaplastic astrocytomas compared to low-grade lesions.
Most high-grade gliomas occur sporadically or without identifiable cause. However, a small proportion (less than 5%) of persons with malignant astrocytoma has a definite or suspected hereditary predisposition. The main hereditary predispositions are mainly neurofibromatosis type I, Li-Fraumeni syndrome, hereditary nonpolyposis colorectal cancer and tuberous sclerosis. Anaplastic astrocytomas have also been associated with previous exposure to vinyl chloride and to high doses of radiation therapy to the brain.
The standard initial treatment is to remove as much of the tumor as possible without worsening neurologic deficits. Radiation therapy has been shown to prolong survival and is a standard component of treatment. There is no proven benefit to adjuvant chemotherapy or supplementing other treatments for this kind of tumor. Although temozolomide is effective for treating recurrent anaplastic astrocytoma, its role as an adjuvant to radiation therapy has not been fully tested.
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